Once a swamp, now a semi-desert, the Great Karoo fascinates almost all who visit. Many wish H G Wells’s time machine existed to take them back to explore the once vast Gondwana continent. Among the men who has the magic to bring this ancient world back to life is S A Museum palaeontologist Dr Roger Smith. While I lived in the Karoo I never missed any talk he might be delivering
One evening, at the Karoo National Park, Roger explained the Karoo’s transition from swamp to dryland. “Way back when the earth was young all the land was on the western side of the globe and the sea on the east. Land bridges joined the great super continent, Gondwana, to another huge landmass in the north, called Pangia,” he said. Then gradually the huge landmass began to break up and the continents drifted apart.
“The best evidence of continental drift is found in the Karoo which 200-million years ago was in the centre of a large landmass and closer to the south pole than it is today. North-flowing rivers, traces of which can still be seen from the air, fed a huge inland sea. South Africa as we know it today had no coast. This only began to appear 100 million years ago. The crack beneath the ocean, which led to continental drift, began 190 million years ago and continues at a rate of 2cm a year,” said Roger.
“The rocks of the Karoo are the curators of this fascinating story. Here the earth’s surface is thickest and best preserved. This is the best place to study the ancient mysteries of history. Karoo rocks also reveal that the beautiful Cape folded mountain belt of the Swartberg began to be formed 300 million years ago and ended 190 million years ago when the dolerite intrusions began. Today, this dolerite forms distinctive caps on Karoo mountains.”